June 5 (HealthDay News) -- A diet rich in omega-3 fatty acids -- found in certain fish, nuts, seeds and vegetable oils -- may help lower blood pressure.

That's the conclusion of a study that examined data from 4,680 people in China, Japan, the United Kingdom and the United States.

Researchers looked at participants' blood pressure and dietary intake of omega-3 fatty acids. After compensating for a number of factors known to affect blood pressure (such as age, weight, exercise, salt intake, gender and alcohol consumption), the researchers concluded that high dietary intake of omega-3 fatty acids was associated with:

• 0.6 mmHg lower systolic blood pressure (top number) and 0.6 mmHg lower diastolic blood pressure (bottom number), on average, for the entire study group.
• About 1.0 mmHg lower systolic blood pressure and 1.0 lower diastolic blood pressure among the 2,238 people who were not on a special diet or taking supplements or medication to treat high blood pressure, heart disease or diabetes.
• About 0.9 mmHg lower systolic blood pressure and 0.9 mmHg lower diastolic blood pressure among the 2,038 people without high blood pressure.

The findings are published in the June issue of the journal Hypertension.

"Foods with omega-3 PFA (polyunsaturated fatty acids) had more of an effect in people who were not already taking medication and had not yet developed high blood pressure," study lead author Dr. Hirotsugu Ueshima, professor and chairman of the department of health science at Shiga University of Medical Science in Japan, said in a prepared statement.

Previous studies found that a population-wide decrease of 2 mmHg of blood pressure could reduce deaths from stroke by about six percent and deaths from coronary heart disease by about four percent.

"With blood pressure, every millimeter counts. The effect of each nutrient is apparently small but independent, so together they can add up to a substantial impact on blood pressure," Ueshima said.

"If you can reduce blood pressure a few millimeters from eating less salt, losing a few pounds, avoiding heavy drinking, eating more vegetables, whole grains and fruits (for their fiber, minerals, vegetable protein and other nutrients) and getting more omega-3 fatty acids, then you've made a big difference," Ueshima said.

SOURCE: June 4, 2007, American Heart Association, news release